1. Field of the Invention
The present invention relates to a press-connecting terminal used in the wiring installed in a vehicle such as an automobile. More particularly, the present invention relates to press-connecting blades of the press-connecting terminal which can be electrically connected to an electric wire, connected to the press-connecting terminal, with a small electrical resistance.
The present application is based on Japanese Patent Application No. Hei. 11-322956, which is incorporated herein by reference.
2. Description of the Related Art
In automobiles having various electronic equipments mounted thereon, press-connecting terminals have been extensively used for connecting the electronic equipments together and for connecting wire harnesses together.
As shown in FIG. 6, a conventional press-connecting terminal 30 includes a connection portion 31 for connection to a mating male terminal (not shown), a press-connection portion 32 for being press-connected to an end portion of an electric wire 21, and retaining piece portions 33 for press-holding the electric wire 2. A resilient contact piece portion 35 for contact with the mating male terminal, inserted into the connection portion 31 through an insertion port 31a in a front end thereof, is provided within the connection portion 31. A lance 36 for retaining the press-connecting terminal, inserted in a connector housing (not shown), against withdrawal, is formed on an upper surface of the connection portion 31, and also a stabilizer 37 for limiting the inserting direction is formed on the upper surface of the connection portion 31.
The press-connecting portion 32 includes two press-connecting blades 41 and 42.
As shown in FIG. 9, the front press-connecting blade 41 is defined or formed by a pair of opposed projecting pieces 44 which are stamped respectively from opposed (right and left) side plates 39 of the press-connecting portion 32, and then are bent inwardly. A press-connecting groove 45 is formed between the opposed projecting pieces 44. The width of this press-connecting groove 45 is smaller than the diameter of a conductor 23 of the electric wire 21.
As shown in FIG. 7, the rear press-connecting blade 42 is formed by stamping a relevant portion of a bottom wall 47 and then by bending it upwardly. This rear press-connecting blade 42 is spaced a predetermined distance from the front press-connecting blade 41. As shown in FIG. 10, a press-connecting groove 49 is also formed in the press-connecting blade 42, and the width of this press-connecting groove is equal to the width of the press-connecting groove 45.
Next, the process of press-connecting the electric wire 21 will be described.
An end portion of the electric wire 21 is press-fitted into the press-connecting blades 41 and 42 from the upper side of the press-connecting portion 32 as indicated by arrow A in FIG. 6. As a result, opposed side edges of each of the press-connecting grooves 45 and 49 cut a sheath 22 of the electric wire 21 to contact the conductor 23, as shown in FIGS. 9 and 10.
Then, the electric wire 21 is fastened by the pair of retaining piece portions (barrel portion) 33 through the sheath 22 as shown in FIG. 8, thus completing the fixing of the electric wire 21 to the press-connecting terminal 30.
In the above conventional press-connecting terminal 30, however, the press-connecting portion 32 is mainly designed to merely firmly press-connect and hold the conductor 23, and the area of contact of each press-connecting blade 41, 42 with the conductor 23 has often been inadequate.
Because of this inadequate contact area, an electrical resistance, developing between the conductor 23 and each press-connecting blade 41, 42, increases to generate heat, so that those members around the press-connecting portion are subjected to deterioration, improper contact and so on, and this has resulted in a problem that the safety of the vehicle is affected.
The present invention seeks to overcome the above problems of the conventional construction, and an object of the present invention is to provide a press-connecting terminal provided with press-connecting blades which can be electrically connected to an electric wire with a small electrical resistance.
To achieve the above object, according to the present invention, there is provided a press-connecting terminal which includes:
a base;
a connection portion, to which a connection terminal of a mating connector is electrically connectable, disposed on the base; and
a press-connecting portion, to which a conductor of an electric wire is electrically connectable, disposed on the base, the press-connecting portion including plural pairs of press-connecting blades, each pair of which have:
a pair of bladed, tapering guide surfaces which slant inwardly downwardly, and
a pair of opposed inner surfaces, between which a gap smaller than a diameter of the conductor of the electric wire is formed, and which downwardly extend respectively from the pair of tapering guide surfaces;
wherein when an electric wire is press-fitted into the gap, the conductor of the electric wire is electrically connected to and held by the plural pairs of press-connecting blades, and
wherein an effective total contact area of the opposed inner surfaces of the press-connecting blades with the conductor is set to a value equal to or greater than a cross-sectional area of the conductor.
In the press-connecting terminal of the above construction, the functions of the press-connecting blades to press-contact and hold the conductor, as well as the electrical connection of the press-connecting blades to the conductor, can be suitably achieved. Accordingly, those members around the press-connecting portion are prevented from being subjected to deterioration, improper contact and so on by heat produced by the electrical resistance developing between the conductor and each press-connecting blade, and therefore the safety of the vehicle is positively prevented from being affected.
In the press-connecting terminal of the above construction, the effective total contact area is such a total of areas that the conductor of the electric wire contacts with the opposed inner surfaces of the press-connecting blades.
Therefore, a necessary width of each of the opposed inner surfaces of the press-connecting blades, a necessary size of the gap, and the necessary number of the press-connecting blades may be determined on the basis of the cross-sectional area of the conductor of the electric wire.
In other words, the effective total contact area may be set on the basis of at least one of the width of each of the opposed inner surfaces, the size of the gap, and the number of the opposed inner surfaces, with respect to the conductor.